Image processing device, image processing method, image processing program and computer-readable recording medium on which the program is recorded

ABSTRACT

An image processing device separates and extracts, when it receives a designation input of a compression processing mode, a character region, a graphic region and a photograph region from input image data. Then, to perform the compression process for the individual region data, if a speed preference mode is set, one of a plurality of compression methods designated for each of the region data which exhibits the highest processing speed is used, if a picture quality preference mode is set, one of a plurality of compression methods designated for each of the region data which exhibits the least picture quality deterioration is used, and if a size preference mode is set, one of a plurality of compression methods designated for each of the region data which exhibits the highest compression ratio is used. Further, for each of character region data from among the extracted region data, the image size is calculated. If the image size is equal to or greater than a threshold value, the MMR compression is used, whereas if the image size is smaller than the threshold value, the Flate compression is used to perform the compression process for the character region data.

[0001] This application is based on Japanese Patent Application No.2002-321406 filed on Nov. 5, 2002, and 2002-339741 filed on Nov. 22,2002, the contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to an image processing device, and moreparticularly to an image processing device which extracts character,graphic and photograph regions from image data acquired by reading anoriginal document and performs image processing for the regions and thenre-synthesizes them to prepare a document image file.

[0004] 2. Description of Related Art

[0005] Image data read by unit of a scanner or a like device has a greatvolume and hence is not suitable for storage or fortransmission/reception directly as it is. Therefore, a suitable imageprocess such as compression is performed for the image data inaccordance with the type of the image. However, in image data acquiredby reading an original document, character regions including characterimages, graphic regions formed from graphic images and photographregions formed from photographs are included in a mixed state.Therefore, there is a problem that, if compression suitable for thephotograph regions is applied to the image data, then this makes it lesseasy to read the characters although the volume decreases, but ifcompression suitable for the character regions is applied, then asufficiently high compression ratio cannot be achieved. Thus, some knownimage processing device extracts character, graphic and photographregions separately from one another from image data of an originaldocument and applies different compressions suitable for the individualregions and then re-synthesizes them to prepare a document image file.According to the image processing device just descried, an image filecan be prepared with a sufficiently reduced volume while an imagequality is maintained (refer to, for example, Japanese Patent Laid-OpenNo. 2001-169120).

[0006] However, depending upon the object of use of the image processingdevice, various cases are possible. In particular, it is desired to givea preference to the processing speed even if the volume or the picturequality of an image file to be outputted is sacrificed. Or, it isdesired to give a preference to the picture quality even if the volumeor the processing speed is sacrificed. Or else, it is desired to reducethe volume even if the picture quality or the processing speed issacrificed. However, an image processing device is not available as yetwhich can automatically execute a compression process which satisfiesany of the demands of users. Also an image processing device is notavailable as yet with which a user can arbitrarily designate acompression processing method to be applied to each of extractedregions.

[0007] Further, in the image processing device described above, if dataof a specific region is processed by a default compression method, thatis, a compression method suitable for the region, then the image sizeafter the compression process of data of a region whose image size issmaller than a predetermined value sometimes becomes greater than thatbefore the compression process. In order to solve the problem, severalmethods are available. According to one of the methods, compressionprocessing is performed using a plurality of compression methods and oneof resulting data which exhibits a minimum image size is adopted (referto, for example, Japanese Patent Laid-Open No. Hei 11-215382). Accordingto another one of the methods, compression processing is not performedfor a region with which the phenomenon described above occurs (refer to,for example, Japanese Patent Laid-Open No. Hei 9-149248). However, theformer method has a problem in that it involves complicated processingbecause it is necessary to perform compression processing for allregions individually using a plurality of compression methods.Meanwhile, the latter method has a problem in that the compression ratioof the image file as a whole is low because compression processing isnot performed for a particular region.

SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide an imageprocessing device wherein, while character, graphic and photographregions are extracted from image data acquired by reading an originaldocument and undergo image processing and then are re-synthesized toprepare a document image file, a suitable compression process can beapplied to data of each region automatically in accordance with a demandof a user regarding to which one of the speed, picture quality andvolume a preference should be given.

[0009] It is another object of the present invention to provide an imageprocessing device of the type just mentioned wherein a method of acompression process to be applied to data of each region can bedesignated arbitrarily by a user.

[0010] It is a further object of the present invention to provide animage processing device of the type mentioned wherein, even whereapplication of a compression process to data of a specific region usinga compression method suitable for the region gives rise to some increaseof the image size after the compression process of data of anotherregion whose image size is smaller than a predetermined value withrespect to the image size before the compression process, imagedeterioration and drop of the processing speed can be suppressed to theminimum thereby to obtain an image of a high compression ratio.

[0011] The objects of the present invention described above are achievedby the following means.

[0012] (1) An image processing device, comprising: a region extractionunit for separating and extracting a character region, a graphic regionand: a photograph region from image data; a region compression unit forperforming a compression process for each of the region data extractedby said region extraction unit; a region synthesis unit for synthesizingthe region data compressed by said region compression unit; and acompression method selection unit for selecting a compression method ofthe compression process to be performed for each of the region dataextracted by said region extraction unit from among a plurality ofcompression methods designated individually for types of the regiondata; said region compression unit performing the compression processfor each of the region data using the compression method selected forthe region data by said compression method selection unit.

[0013] (2) An image processing device, comprising: a region extractionunit for separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression unit forperforming a compression process for each of the region data extractedby said region extraction unit; a region synthesis unit for synthesizingthe region data compressed by said region compression unit; and acompression process mode setting unit for setting a speed preferencemode as a compression process mode; said region compression unit using,when the speed preference mode is set by said compression process modesetting unit, one of a plurality of compression methods designated foreach of the region data which exhibits the highest processing speed toperform the compression process for the individual region data.

[0014] (3) An image processing device, comprising: a region extractionunit for separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression unit forperforming a compression process for each of the region data extractedby said region extraction unit; a region synthesis unit for synthesizingthe region data compressed by said region compression unit; and acompression process mode setting unit for setting a picture qualitypreference mode as a compression processing mode; said regioncompression unit using, when the picture quality preference mode is setby said compression process mode setting unit, one of a plurality ofcompression methods designated for each of the region data whichexhibits the least picture quality deterioration to perform thecompression process for the individual region data.

[0015] (4) An image processing device, comprising: a region extractionunit for separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression unit forperforming a compression process for each of the region data extractedby said region extraction unit; region synthesis unit for synthesizingthe region data compressed by said region compression unit; and acompression process mode setting unit for setting a size preference modeas a compression processing mode; said region compression unit using,when the size preference mode is set by said compression process modesetting unit, one of a plurality of compression methods designated foreach of the region data which exhibits the highest compression ratio toperform the compression process for the individual region data.

[0016] (5) An image processing device, comprising: a region extractionunit for separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression unit forperforming a compression process for each of the region data extractedby said region extraction unit; a region synthesis unit for synthesizingthe region data compressed by said region compression unit; and acompression process mode setting unit for setting a speed preferencemode, a picture quality preference mode or a size preference mode as acompression processing mode; said region compression unit using, whenthe speed preference mode is set by said compression process modesetting unit, one of a plurality of compression methods designated foreach of the region data which exhibits the highest processing speed toperform the compression process for the individual region data, saidregion compression unit using, when the picture quality preference modeis set by said compression process mode setting unit, one of a pluralityof compression methods designated for each of the region data whichexhibits the least picture quality deterioration to perform thecompression process for the individual region data, and said regioncompression unit using, when the size preference mode is set by saidcompression process mode setting unit, one of a plurality of compressionmethods designated for each of the region data which exhibits thehighest compression ratio to perform the compression process for theindividual region data.

[0017] (6) An image processing device, comprising: a object extractionunit for interpreting a document file described in a page descriptionlanguage, and extracting a object which is a component of the documentfile, a object compression unit for performing a compression process foreach of the object data extracted by said object extraction unit; aobject synthesis unit for synthesizing the object data compressed bysaid object compression unit; and a compression methods election unitfor selecting a compression method of the compression process to beperformed for each of the object data extracted by said objectextraction unit from among a plurality of compression methods designatedindividually for types of the object data; said object compression unitperforming the compression process for each of the object data using thecompression method selected for the object data by said compressionmethod selection unit.

[0018] (7) An image processing method, comprising: a region extractionstep of separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression method selection step of selecting a compression method ofthe compression process to be performed for each of the region dataextracted by said region extraction step from among a plurality ofcompression methods designated individually for types of the regiondata; said region compression step performing the compression processfor each of the region data using the compression method selected forthe region data by said compression method selection step.

[0019] (8) An image processing method, comprising: a region extractionstep of separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression process mode setting step of setting a speed preference modeas a compression process mode; said region compression step using, whenthe speed preference mode is set by said compression process modesetting step, one of a plurality of compression methods designated foreach of the region data which exhibits the highest processing speed toperform the compression process for the individual region data.

[0020] (9) An image processing method, comprising: a region extractionstep of separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression process mode setting step of setting a picture qualitypreference mode as a compression processing mode; said regioncompression step using, when the picture quality preference mode is setby said compression process mode setting step, one of a plurality ofcompression methods designated for each of the region data whichexhibits the least picture quality deterioration to perform thecompression process for the individual region data.

[0021] (10) An image processing method, comprising: a region extractionstep of separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression process mode setting step of setting a size preference modeas a compression processing mode; said region compression step using,when the size preference mode is set by said compression process modesetting step, one of a plurality of compression methods designated foreach of the region data which exhibits the highest compression ratio toperform the compression process for the individual region data.

[0022] (11) An image processing method, comprising: a region extractionstep of separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression process mode setting step of setting a speed preferencemode, a picture quality preference mode or a size preference mode as acompression processing mode; said region compression step using, whenthe speed preference mode is set by said compression process modesetting step, one of a plurality of compression methods designated foreach of the region data which exhibits the highest processing speed toperform the compression process for the individual region data, saidregion compression step using, when the picture quality preference modeis set by said compression process mode setting step, one of a pluralityof compression methods designated for each of the region data whichexhibits the least picture quality deterioration to perform thecompression process for the individual region data, and said regioncompression step using, when the size preference mode is set by saidcompression process mode setting step, one of a plurality of compressionmethods designated for each of the region data which exhibits thehighest compression ratio to perform the compression process for theindividual region data.

[0023] (12) An image processing program for causing an image processingdevice to execute: a region extraction step of separating and extractinga character region, a graphic region and a photograph region from imagedata; a region compression step of performing a compression process foreach of the region data extracted by said region extraction step; aregion synthesis step of synthesizing the region data compressed by saidregion compression step; and a compression method selection step ofselecting a compression method of the compression process to beperformed for each of the region data extracted by said regionextraction step from among a plurality of compression methods designatedindividually for types of the region data; said region compression stepperforming the compression process for each of the region data using thecompression method selected for the region data by said compressionmethod selection step.

[0024] (13) An image processing program for causing an image processingdevice to execute: a region extraction step of separating and extractinga character region, a graphic region and a photograph region from imagedata; a region compression step of performing a compression process foreach of the region data extracted by said region extraction step; aregion synthesis step of synthesizing the region data compressed by saidregion compression step; and a compression process mode setting step ofsetting a speed preference mode as a compression process mode; saidregion compression step using, when the speed preference mode is set bysaid compression process mode setting step, one of a plurality ofcompression methods designated for each of the region data whichexhibits the highest processing speed to perform the compression processfor the individual region data.

[0025] (14) An image processing program for causing an image processingdevice to execute: a region extraction step of separating and extractinga character region, a graphic region and a photograph region from imagedata; a region compression step of performing a compression process foreach of the region data extracted by said region extraction step; aregion synthesis step of synthesizing the region data compressed by saidregion compression step; and a compression process mode setting step ofsetting a picture quality preference mode as a compression processingmode; said region compression step using, when the picture qualitypreference mode is set by said compression process mode setting step,one of a plurality of compression methods designated for each of theregion data which exhibits the least picture quality deterioration toperform the compression process for the individual region data.

[0026] (15) An image processing program for causing an image processingdevice to execute: a region extraction step of separating and extractinga character region, a graphic region and a photograph region from imagedata; a region compression step of performing a compression process foreach of the region data extracted by said region extraction step; aregion synthesis step of synthesizing the region data compressed by saidregion compression step; and a compression process mode setting step ofsetting a size preference mode as a compression processing mode; saidregion compression step using, when the size preference mode is set bysaid compression process mode setting step, one of a plurality ofcompression methods designated for each of the region data whichexhibits the highest compression ratio to perform the compressionprocess for the individual region data.

[0027] (16) An image processing program for causing an image processingdevice to execute: a region extraction step of separating and extractinga character region, a graphic region and a photograph region from imagedata; a region compression step of performing a compression process foreach of the region data extracted by said region extraction step; aregion synthesis step of synthesizing the region data compressed by saidregion compression step; and a compression process mode setting step ofsetting a speed preference mode, a picture quality preference mode or asize preference mode as a compression processing mode; said regioncompression step using, when the speed preference mode is set by saidcompression process mode setting step, one of a plurality of compressionmethods designated for each of the region data which exhibits thehighest processing speed to perform the compression process for theindividual region data, said region compression step using, when thepicture quality preference mode is set by said compression process modesetting step, one of a plurality of compression methods designated foreach of the region data which exhibits the least picture qualitydeterioration to perform the compression process for the individualregion data, and said region compression step using, when the sizepreference mode is set by said compression process mode setting step,one of a plurality of compression methods designated for each of theregion data which exhibits the highest compression ratio to perform thecompression process for the individual region data.

[0028] (17) A computer-readable recording medium on which the imageprocessing program according to (16) is recorded.

[0029] (18) An image processing device, comprising: a region extractionunit for separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression unit forperforming a compression process for each of the region data extractedby said region extraction unit; a region synthesis unit for synthesizingthe region data compressed by said region compression unit; and an imagesize calculation unit for calculating an image size of specific regiondata extracted by said region extraction unit; said region compressionunit using, when the image size of the specific region data calculatedby said image size calculation unit is equal to or greater than athreshold value, a first compression method to perform the compressionprocess for the specific region data, and said region compression unitusing, when the image size of the specific region data calculated bysaid image size calculation unit is smaller than the threshold value, asecond compression method to perform the compression process for thespecific region data.

[0030] (19) An image processing device, comprising: a object extractionunit for interpreting a document file described in a page descriptionlanguage, and extracting a object which is a component of the documentfile, a object compression unit for performing a compression process foreach of the object data extracted by said object extraction unit; aobject synthesis unit for synthesizing the object data compressed bysaid object compression unit; an image size calculation unit forcalculating an image size of the object data extracted by said objectextraction unit; and a compression method selection unit for selecting acompression method of the compression process to be performed for eachof the object data extracted by said object extraction unit inproportion to the image size of the object data calculated by said imagesize calculation unit from among a plurality of designated compressionmethods; said object compression unit performing the compression processfor each of the object data using the compression method selected forthe object data by said compression method selection unit.

[0031] (20). An image processing method, comprising: a region extractionstep of separating and extracting a character region, a graphic regionand a photograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and an imagesize calculation step of calculating an image size of specific regiondata extracted by said region extraction step; said region compressionstep using, when the image size of the specific region data calculatedby said image size calculation step is equal to or greater than athreshold value, a first compression method to perform the compressionprocess for the specific region data, and said region compression stepusing, when the image size of the specific region data calculated bysaid image size calculation step is smaller than the threshold value, asecond compression method to perform the compression process for thespecific region data.

[0032] (21) An image processing method, comprising: a character regionextraction step of separating and extracting character regions fromimage data; an image size calculation step of calculating an image sizeof each of the character region data extracted by said character regionextraction step; a compression method selection step of selecting, whenthe image size of each of the character region data calculated by saidimage size calculation step is equal to or greater than a thresholdvalue, the MMR compression as a compression method but selecting, whenthe image size of each of the character region data calculated by saidimage size calculation step is smaller than the threshold value, theFlate compression as a compression method; and a region compression stepof performing a compression process for each of the character regiondata using the compression method selected by said compression methodselection step.

[0033] (22) An image processing program for causing an image processingdevice to execute: a region extraction step of separating and extractinga character region, a graphic region and a photograph region from imagedata; a region compression step of performing a compression process foreach of the region data extracted by said region extraction step; aregion synthesis step of synthesizing the region data compressed by saidregion compression step; and an image size calculation step ofcalculating an image size of specific region data extracted by saidregion extraction step; said region compression step using, when theimage size of the specific region data calculated by said image sizecalculation step is equal to or greater than a threshold value, a firstcompression method to perform the compression process for the specificregion data, and said region compression step using, when the image sizeof the specific region data calculated by said image size calculationstep is smaller than the threshold value, a second compression method toperform the compression process for the specific region data.

[0034] (23) The computer-readable recording medium on which the imageprocessing program according to (22) is recorded.

[0035] (24) An image processing program for causing an image processingdevice to execute: a character region extraction step of separating andextracting character regions from image data; an image size calculationstep of calculating an image size of each of the character region dataextracted by said character region extraction step; a compression methodselection step of selecting, when the image size of each of thecharacter region data calculated by said image size calculation step isequal to or greater than a threshold value, the MMR compression as acompression method but selecting, when the image size of each of thecharacter region data calculated by said image size calculation step issmaller than the threshold value, the Flate compression as a compressionmethod; and a region compression step of performing a compressionprocess for each of the character region data using the compressionmethod selected by said compression method selection step.

[0036] (25) The computer-readable recording medium on which the imageprocessing program according to (24) is recorded.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]FIG. 1 is a block diagram showing a general configuration of animage processing system including an image processing device accordingto a first embodiment of the present invention;

[0038]FIG. 2 is a block diagram showing a configuration of the imageprocessing device 1 a shown in FIG. 1;

[0039]FIG. 3 is a schematic view illustrating a concept of an example ofan image process by the image processing device 1 a;

[0040]FIG. 4 is a flow chart illustrating a procedure of the imageprocess of the image processing device 1 a;

[0041]FIG. 5 is a schematic view showing an example of a setting screenfor a compression process displayed on an operation panel of anoperation section 103 of the image processing device 1 a;

[0042]FIG. 6 is a flow chart illustrating a procedure of a characterregion process of the image processing device 1 a;

[0043]FIG. 7 is a flow chart illustrating a procedure of a graphicregion process of the image processing device 1 a;

[0044]FIG. 8 is a flow chart illustrating a procedure of a photographregion process of the image processing device 1 a;

[0045]FIG. 9 is a flow chart illustrating a procedure of an imageprocess of an image processing device 1 b according to a secondembodiment of the present invention;

[0046]FIG. 10 is a schematic view showing an example of a setting screenfor a compression process displayed on an operation panel of anoperation section 103 of the image processing device 1 b;

[0047]FIG. 11 is a flow chart illustrating a procedure of a characterregion process of the image processing device 1 b;

[0048]FIG. 12 is a flow chart illustrating a procedure of a graphicregion process of the image processing device 1 b;

[0049]FIG. 13 is a flow chart illustrating a procedure of a photographregion process of the image processing device 1 b;

[0050]FIG. 14 is a flow chart illustrating a procedure of an imageprocess of an image processing device 1 c according to a thirdembodiment of the present invention; and

[0051]FIG. 15 is a flow chart illustrating a procedure of a characterregion process of the image processing device 1 c.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] In the following, embodiments of the present invention aredescribed in detail with reference to the drawings.

[0053]FIG. 1 is a block diagram showing a general configuration of animage processing system including an image processing device accordingto a first embodiment of the present invention. Referring to FIG. 1, theimage processing system shown includes an image processing device 1 a, ascanner 2 serving as an image inputting source device, and a file server3 serving as an image outputting destination device. The components ofthe image processing system just mentioned are connected for mutualcommunication through a computer network 4. It is to be noted that thetypes and the numbers of such device to be connected to the computernetwork 4 are not limited to those shown in FIG. 1.

[0054]FIG. 2 is a block diagram showing a configuration of the imageprocessing device 1 a according to the present embodiment. Referring toFIG. 2, the image processing device 1 a includes a control section 101,a storage section 102, an operation section 103, an input interfacesection 104, an output interface section 105, a region extractionsection 106, an image processing section 107, a region synthesis section108 and a file format conversion section 109. The components mentionedof the image processing device 1 a are connected to one another by a bus110 for delivering signals therealong.

[0055] The control section 101 is a CPU and performs control of thecomponents described, various arithmetic operation processes and othernecessary processes in accordance with a program. The storage section102 includes a ROM for storing various programs and parameters inadvance, a RAM serving as a working area for storing a program or data,a hard disk used to store various programs and parameters andtemporarily store image data and other necessary data obtained by imageprocessing, and some other necessary devices.

[0056] The operation section 103 includes keys, an operation panel andso forth used to set an output region, a type of an image process, acolor mode, a format of an output file, a transmission destination andso forth and issue an instruction to start an operation and so forth.Here, the setting of an output region is performed by selecting whethersome or all of extracted character, graphic and photograph regionsshould be outputted. The setting of a type of an image process isperformed by selecting whether or not some of binarization, colorsubtraction, resolution conversion, smoothing, compression and otherprocesses should be performed as a type of an image process to beperformed for an extracted region. Thereupon, for the compressionprocess, a compression method to be performed for data of each region isselected as hereinafter described. The setting of a color mode isperformed by selecting a color mode or a monochrome mode and a grayscale of an output file. The setting of a format of an output file isperformed by selecting one of file formats for an output file. It is tobe noted that, as a format for an output file, document formats ofvarious types of document preparation software and formats for universaluse such as the Postscript (registered trademark) and the PDF can beapplied. The setting of a transmission destination is performed byinputting an IP address, a host computer name, a mail address and othernecessary information of an device of an image outputting destination.

[0057] The input interface section 104 is an interface for receiving aninput of image data from an external image inputting source device. Theoutput interface section 105 is an interface for transmitting an outputfile to an external image outputting destination device.

[0058] The region extraction section 106 performs a process ofseparating and extracting character regions, graphic regions andphotograph regions from input image data. The image processing section107 includes a character region processing section 107 a, a graphicregion processing section 107 b and a photograph region processingsection 107 c, and performs appropriate image processes for individualregion data of the extracted character, graphic and photograph regions.The region synthesis section 108 synthesizes the character, graphic andphotograph data after the image processes to prepare composite imagedata of an internal file format. The file format conversion section 109converts the produced composite image data of the internal file formatinto composite image data of a set output file format.

[0059] The scanner 2 reads an original document to acquire image dataand transmits the acquired image data to the image processing device.

[0060] The file server 3 is a computer, and stores a file receivedthrough the computer network and transfers the stored file to anotherdevice on the computer network in response to a transfer request.

[0061] The computer network 4 is formed from a LAN in which a computerand peripheral equipment, network device and so forth are connected inaccordance with the specifications of the Ethernet (registeredtrademark), Token Ring, FDDI or the like, or a WAN wherein LANs areinterconnected by a dedicated line, or the like.

[0062] Now, an outline of image processing executed by the imageprocessing device 1 a according to the present invention is described.FIG. 3 is a view illustrating a concept of an example of imageprocessing by the image processing device 1 a. As shown in (a) of FIG.3, input image data obtained by reading in an original document from thescanner 2 includes a character region or regions each including acharacter image, a graphic region or regions each including a graphicimage and a photograph region or regions each including a photographimage. When it is intended to compress such image data of a great volumeto reduce the volume and store the image data of the reduced volume intothe file server 3, if the entire image data is compressed uniformly asit is, then where compression suitable for a photograph region isperformed, although the volume decreases, it becomes less easy to readthe characters because of deterioration of the image. However, ifcompression suitable for a character region is applied, then asufficiently high compression ratio cannot be achieved. Therefore, theimage processing device 1 a separates and extracts character regions,graphic regions and photograph regions from input image data receivedfrom the scanner 2 ((b) of FIG. 3). Then, the image processing device 1a performs suitable compression processes suitable for the types of theregions for the extracted region data and re-synthesizes the compressedregion data to prepare composite image data ((c) of FIG. 3). Thereafter,the image processing device 1 a converts the composite image data intocomposite image data of a predetermined file format and transmits theconverted data to the file server 3.

[0063] Now, an outline of operation of the entire image processingsystem according to the present embodiment is described. FIG. 4 is aflow chart illustrating a procedure of image processing of the imageprocessing device 1 a according to the present embodiment. Referring toFIG. 4, if a designation input of a compression method for a compressionprocess to be applied to region data of each of character regions,graphic regions and photograph regions to be extracted is received (YESat step S101), then the image processing device 1 a sets compressionmethods to be applied to the individual region data in accordance withthe input (S102). Then, the image processing device 1 a waits until animage process starting instruction is received (NO at step S103). FIG. 5is a view showing an example of a compression process setting screen 103a displayed on the operation panel of the operation section 103 of theimage processing device 1 a. Referring to FIG. 5, touch keys for“Compression method designation”, “MMR”, “JBIG”, “Flate”, “JPEG”,“Default” and so forth are displayed on the compression process settingscreen 103 a. When the user wants to designate compression methods forcompression processes to be applied to the individual region data, itwill first depress the “Compression method designation” key, and thendepress, for each of the character, graphic and photograph regions, adesired compression method key to designate the compression methodsindividually for the region data.

[0064] Here, the compression method is a type of a compression form(compression format) to be used for a compression process for eachregion data. In the present embodiment, the MMR compression or the JBIGcompression can be designated for character region data while the Flatecompression or the JPEG compression can be designated for graphic regiondata and photograph region data. The MMR compression and the JBIGcompression are compression methods (both reversible compressions)suitable for an image which has many variation points such as acharacter image. The MMR compression has a characteristic that thecompression speed is higher than that of the JBIG compression while theJBIG compression has another characteristic that it is superior in thepicture quality and the compression ratio to the MMR compression.Meanwhile, the Flate compression and the JEPG compression arecompression methods suitable for graphic and photograph images. Sincethe JPEG compression is irreversible compression, it has characteristicsthat the compression ratio is higher than that of the Flate compressionwhich is reversible compression and that the compression speed is higherthan that of the Flate compression. However, since the JPEG compressionis irreversible compression, it has a further characteristic that it isinferior in the picture quality to the Flate compression and, althoughthe picture quality deterioration is not noticeable with a natural imagesuch as a photograph image, it is notice able with a line drawing suchas a graphic image. If the user designates desired compression methodsfor the individual region data taking the characteristics of thecompression methods described above into consideration, then thearbitrary compression processes can be applied to the individual regiondata extracted from the input data. It is to be noted that, if adesignation input of a compression method from the user is not receivedat step S101 (NO at step S101), then compression processes for theindividual region data are performed using default compression methodsas hereinafter described.

[0065] Referring back to FIG. 4, if the image processing device 1 athereafter accepts an input of a starting instruction through theoperation section 103 from the user (YES at step S103), then ittransmits an original reading instruction to the scanner 2 through theinput interface section 104 (S104) and then waits until image data isreceived from the scanner 2 (NO at step S105). When an original readinginstruction is received from the image processing device 1 a, thescanner 2 reads an original document set at a predetermined position toacquire image data of the original document and transmits the acquiredimage data to the image processing device 1 a.

[0066] The image processing device 1 a receives the image data from thescanner 2 through the input interface section 104 (YES at step S105) andstores the received image data into the storage section 102. It is to benoted that the designation of compression processing methods describedabove may otherwise be performed after image data is received from thescanner. In this instance, the steps S101 to S103 described above areexecuted after the steps S104 to S106. Further, the image processstarting instruction may be inputted from some other device on thecommunication network 4 or directly from the scanner 2. In thisinstance, the steps S104 and S105 described above are omitted.

[0067] Then, the image processing device 1 a separates characterregions, graphic regions and photograph regions from the input imagedata by unit of the region extraction section 106 to extract individualregion data (S106). The method of extracting region data from inputimage data is not limited particularly, but a known method can be used.For example, the following methods can be used.

[0068] In particular, the region extraction section 106 is used todiscriminate a character region or regions from input image data toextract character region data and stores the character region data intothe storage section 102 together with position information of thecharacter region or regions. As a method of discriminating a characterregion, for example, the following method can be used. In particular, aregion in a circumscribed rectangle of an edge pixel group wherein thedistance between edge pixels of edge image data obtained from image datais smaller than a predetermined pixel number is extracted. Then based ona characteristic that a character region includes a lager number ofoblique edge components in a small area, oblique edge components fromamong frequency components included in the region of the circumscribedrectangle are calculated as a characteristic amount. Then, a characterregion is discriminated based on the content of the oblique edgecomponents.

[0069] Then, the region extraction section 106 now complements theextracted character regions with peripheral pixels to producenon-character image data from the input image data and stores thenon-character image data into the storage section 102. Then, the regionextraction section 106 discriminates a graphic region or regions fromthe non-character image data to extract graphic region data and storesthe graphic region data into the storage section 102 together withposition information of the graphic region or regions. As a method ofdiscriminating a graphic region from non-characteristic image data, thefollowing can be used. In particular, based on a characteristic that thebrightness distribution in a graphic region is uniform to some degreewhile the brightness distribution in a photograph region exhibits avariance, a brightness histogram is produced for each line in two mainand sub scanning directions with regard to all pixels in a regiondivided by an edge image from edge image data obtained from brightnessimage data to calculate a degree of dispersion in brightness to make adistinction between a graphic region and a photograph region.

[0070] Then the region extraction section 106 complements the extractedgraphic region or regions of the non-character image data withperipheral pixels, extracts photograph region data from thenon-character image data and stores the photograph region data into thestorage section 102 together with position information of the photographregion or regions.

[0071] Thereafter, the image processing device 1 a uses the imageprocessing section 107 to perform image processes suitable for theregion types for the individual region data extracted at step S104(steps S108 to S110).

[0072]FIG. 6 is a flow chart illustrating a procedure of the characterregion process of the image processing device 1 a according to thepresent embodiment. Referring to FIG. 6, the image processing device 1 areads out character region data from the storage section 102 and usesthe character region processing section 107 a to perform a preprocessfor the character region data (S201). More particularly, the characterregion processing section 107 a detects a character color for each ofthe extracted character region data and binarizes the character regiondata to convert the character region data into 1-bit data. Then, thecharacter region processing section 107 a performs a compression processfor each of the character region data in accordance with the compressionmethod for the character position data designated at step S101 (S202 toS205). In particular, if the MMR compression is designated for thecharacter region data at step S101 (YES at step S202 and YES at stepS203), then the MMR compression is performed for the character regiondata (S204). However, if the JBIG compression is designated (YES at stepS202 and NO at step S203), then the JBIB compression is performed(S205). On the other hand, if no compression method is designated atstep S101 (NO at step S202), then the MMR compression which is defaultcompression is performed for the character region data (S204). Each ofsuch character region data for which the compression process has beenperformed is stored into the storage section 102 together with colorinformation, position information and other necessary informationrelating thereto.

[0073]FIG. 7 is a flow chart illustrating a procedure of the graphicregion process of the image processing device 1 a according to thepresent embodiment. Referring to FIG. 7, the image processing device 1 areads out graphic data from the storage section 102 and uses the graphicregion processing section 107 b to perform a preprocess such as aresolution conversion process, a smoothing process and a primary colorprocess for the graphic region data (S301). Then, if the Flatecompression is designated for the graphic image data at step S101 (YESat step S302 and YES at step S303), then the Flate compression isperformed for the graphic data (S304). However, if the JPEG compressionis designated (YES at step S302 and NO at step S303), then the JPEGcompression is performed for the graphic region data (S305). On theother hand, if no compression method is designated at step S101 (NO atstep 302), then the Flate compression which is default compression isperformed for the graphic region data (S304). Each of the graphic regiondata for which the compression process has been performed is stored intothe storage section 102 together with position information and so forthrelating thereto.

[0074]FIG. 8 is a flow chart illustrating a procedure of the photographregion process of the image processing device 1 a according to thepresent embodiment. Referring to FIG. 8, the image processing device 1 areads out photograph region data from the storage section 102 and usesthe photograph region processing section 107 c to perform a preprocesssuch as a resolution conversion process and a smoothing process for thephotograph region data (S401). Then, if the JPEG compression isdesignated for the photograph image data at step S101 (YES at step S402and YES at step S403), then the JPEG compression is performed for thephotograph region data (S404). However, if the Flate compression isdesignated (YES at step S402 and NO at step S403), then the Flatecompression is performed for the photograph region data (S405). On theother hand, if no compression method is designated at step S101 (NO atstep S402), then the JPEG compression which is default compression isperformed for the photograph region data (S404). Each of the photographregion data for which the compression process has been performed isstored into the storage section 102 together with position informationthereof and so forth.

[0075] It is to be noted that, in FIG. 4, the image processing device 1a may execute the character region process (S107), graphic regionprocess (S108) and photograph region process (S109) in any order.

[0076] Thereafter, the image processing device 1 a uses the regionsynthesis section 108 to synthesize the region data obtained by theimage process described above based on the position information of themto acquire composite image data and stores the composite image data intothe storage section 102 (S110). Further, the image processing devicelauses the file format conversion section 109 to convert the compositeimage data into composite image data of the set output file format(S111) and transmits the resulting output file (document image file) tothe file server 3 through the output interface section 105 and thecomputer network 4 (S112).

[0077] The file server 3 receives the output file from the imageprocessing device 1 a through the computer network 4 and stores thereceived file into a predetermined directory of the storage device suchas a hard disk. Then, if a transfer request for the file is receivedfrom a different device on the computer network 4, then the imageprocessing device 1 a transfers the stored file to the different devicethrough the computer network 4.

[0078] Now, an image processing device according to a second embodimentof the present invention is described. FIG. 9 is a flow chartillustrating a procedure of an image process of the image processingdevice 1 b according to the second embodiment of the present invention.In the present embodiment, the image processing device 1 b has aconfiguration similar to that of the image processing device 1 aaccording to the first embodiment described hereinabove and is connectedto a scanner 2 and a file server 3 for mutual communication by acomputer network 4 similarly to the image processing device 1 a.

[0079] Referring to FIG. 9, if a designation input of a compressionprocessing mode for compression processes to be performed for individualregion data is received (YES at step S501), then the image processingdevice 1 b sets a compression processing mode in accordance with theinput (S502). Then, the image processing device 1 a waits until an imageprocess starting instruction is received (NO at step S505). FIG. 10 is aview showing an example of a compression process setting screendisplayed on the operation panel of the operation section 103 of theimage processing device 1 b. Referring to FIG. 10, the compressionprocess setting screen 103 b additionally displays, when compared withthe compression process setting screen 103 a by the image processingdevice 1 a of the first embodiment described hereinabove, “Compressionprocessing mode designation” and “Speed preference”, “Picture qualitypreference” and “Size preference” keys. When the user wants to designatea compression processing mode for a compression process to be performedfor each region data, it will depress the “Compression processing modedesignation” key and further depress a desired one of the compressionprocessing mode keys to designate a mode of the key.

[0080] Here, the compression processing mode makes it possible todesignate a factor which should be used preferentially when each ofregion data is to be compressed by designating a mode. In the presentembodiment, the compression processing mode can be selectivelydesignated from among a speed preference mode, a picture qualitypreference mode and a size preference mode. The speed preference mode isa mode in which a compression process is performed at the highestprocessing speed, and in the speed preference mode, each region data iscompressed through application of a compression method which exhibitsthe highest processing speed. The picture quality preference mode is amode in which image data obtained by a compression process exhibits thehighest picture quality, and in the picture quality mode, each regiondata is compressed through application of a compression process whichexhibits the least picture quality deterioration. The size preferencemode is a mode in which image data obtained by a compression processexhibits the smallest size, and in the size preference mode, each regiondata is compressed through application of a compression method whichexhibits the highest compression ratio. Consequently, even if the userdoes not have particular knowledge regarding a compression method to beperformed for each region data, only if it designates the compressionprocessing mode, then a desired compression process can be executed.

[0081] Referring back to FIG. 9., if a designation input of acompression method to be performed for each region data is received inplace of a designation input of a compression processing mode for animage process (NO at step S501 and YES at step S503), then the imageprocessing device 1 b sets the compression methods to be performed forthe individual region data in accordance with the input (S504). Then,the image processing device 1 a waits until an image process startinginstruction is received (NO at step S505).

[0082] Then, when an input of an image process starting instruction isaccepted (YES at step S505), then the image processing device 1 atransmits an original reading instruction to the scanner 2 (S506) andwaits that it receives image data from the scanner 2 (S507). Then, theimage processing device 1 a extracts individual region data from thereceived input image data (S508) and then performs image processessuitable for the region types for the extracted region data (S509 toS511).

[0083]FIG. 11 is a flow chart illustrating a procedure of the characterregion process of the image processing device 1 b according to thepresent embodiment. Referring to FIG. 11, the image processing device 1b first performs a preprocess for character region data (S601) and thenperforms a suitable compression process for the character region data inaccordance with the compression processing mode designated at step S501(S602 to S607). In particular, if the speed preference mode isdesignated at step S501 (YES at step S602), then the image processingdevice 1 b performs, from between the MMR compression and the JBIGcompression, the MMR compression having a higher compression speed thanthe JBIG compression for the character region data (S603). Meanwhile, ifthe picture quality preference mode is designated at step S501 (NO atstep S602 and YES at step S604), then the image processing device 1 bperforms the JBIB compression (S606) which exhibits lower deteriorationthan the MMR compression. However, if the size preference mode isdesignated (NO at step S602, NO at step S604 and YES at step S606), theimage processing device 1 b performs the JBIG compression which exhibitsa higher compression ratio than the MMR compression (S607)

[0084] On the other hand, if the compression processing mode is notdesignated at step S501 and a compression method is designated at stepS503 (NO at step S602, NO at step S604, NO at step S606 and YES at stepS608), then the image processing device 1 b performs a compressionprocess for the character region data in accordance with the compressionmethod for the character region data designated at step S503 (S609 toS611). However, if neither the compression processing mode nor acompression method is designated at step S501 or S503 (NO at step S602,NO at step S604, NO at step S606 and NO at step S608), then the imageprocessing device 1 b performs the MMR compression which is a defaultprocess for the character region data (S610).

[0085]FIGS. 12 and 13 are flow charts illustrating procedures of agraphic region process and a photograph region process according thepresent embodiment, respectively. Referring to FIGS. 12 and 13, theimage processing device 1 b performs a preprocess for graphic orphotograph region data (S701 or S801). Then, if the speed preferencemode is designated at step S501 (YES at step S702 or YES at step S802),then the image processing device 1 b performs, from between the Flatecompression and the JPEG compression, the JPEG compression whichexhibits a higher compression speed than the Flate compression for thegraphic or photograph region data (S703 or S803). On the other hand, ifthe picture quality preference mode is designated at step S501 (NO atstep S702 and YES at step S704 or NO at step S802 and YES at step S804),then the Flate compression which exhibits less picture qualitydeterioration than the JPEG compression is performed (S705 or S805).However, if the size preference mode is designated (NO at step S702, NOat step S704 and YES at step S706 or NO at step S802, NO at step S804and YES at step S806), then the JPEG compression which exhibits a highercompression ratio than the Flate compression is performed (S707 orS807).

[0086] On the other hand, if the compression process mode is notdesignated at step S501 and no compression method is designated at stepS503 (NO at step S703, NO at step S704, NO at step 706 and YES at stepS708 or NO at step S802, NO at step S804, NO at step S806 and YES atstep S808), then the image processing device 1 b performs a compressionprocess for the graphic or photograph region data in accordance with thecompression method for the graphic or photograph region data designatedat step S503 (steps S709 to S711 or S809 to S811). However, if neitherthe compression process mode nor a compression method is designated atstep S501 or S503 (NO at step S702, NO at step S704, NO at step S706 andNO at step S708 or NO at step S802, NO at step S804, NO at step S806 andNO at step S808), then the image processing device 1 b performs theFlate compression or the JPEG compression, which is default compression,for the graphic or photograph region data (S710 or S810).

[0087] Referring now to FIG. 9, the image processing device 1 bthereafter synthesizes the region data obtained by the image processdescribed above based on the position information of the same to acquirecomposite image data (S512). Then, the image processing device 1 bconverts the composite image data into composite image data of theoutput file format (S513) and transmits the resulting output file to thefile server 3 (S514).

[0088] In the second embodiment described above, one compression processmode is designated for the entire image process. However, the presentinvention is not limited to this and another configuration may beapplied which makes it possible to designate a compression processingmode for each region data such that, for example, the speed preferencemode is designated for character region data whereas the picture qualitypreference mode is designated for graphic and photograph region data.

[0089] In the embodiment described above, the MMR compression or theJBIG compression is performed for character region data whereas theFlate compression or the JPEG compression is performed for graphicregion data and photograph region data. However, in the presentinvention, the compression methods which may be applied to such regiondata are not limited to them, but any combination of various compressionmethods may be applied to each region data.

[0090] Now, an image processing device according to a third embodimentof the present invention is described. The image processing device 1 caccording to the present embodiment has a configuration similar to thatof the image processing device 1 a according to the first embodimentdescribed hereinabove. In particular, the image processing device 1 c isconnected to a scanner 2 and a file server 3 for mutual communicationthrough a computer network 4 similarly to the image processing device 1a.

[0091] Referring to FIG. 3, while a compression method suitable for eachextracted region data is applied to a compression process for the regiondata, one of compression methods suitable for character region data tobe applied to a compression process for the character region data is theMMR compression. The MMR compression is reversible compression and cansuppress deterioration of a character image, and exhibits a highprocessing speed and exhibits a higher compression ratio than the otherreversible compressions such as the MH compression, MR compression andFlate compression. However, the MMR compression has a problem in that,from an algorithm thereof, where it is applied to character region datahaving a size smaller than a predetermined image size, the image sizeafter the compression process is greater than that before thecompression process. In particular, refer to (a) and (b) of FIG. 3, ifcharacter region data having a great image size such as character regiondata of a character region (1) is MMR compressed, then a good processingeffect is obtained in terms of the picture quality, processing speed andcompression ratio. However, if character region data of such a smallsize as in another character region (2) or (3) is MMR compressed, thenthe image size reversely increases after the compression when comparedwith that before the compression. In the present embodiment, the problemdescribed is solved by changing over the compression method such that,to character region data having such a small size as described above,the Flate compression is applied so that, in whatever the image sizethereof is small, the image size thereof after the compression processdoes not become greater than that before the compression process.

[0092]FIG. 14 is a flow chart illustrating a procedure of the imageprocess of the image processing device 1 c according to the presentembodiment. Referring to FIG. 14, the image processing device 1 c waitsuntil an image process starting instruction is received (NO at stepS901). When an input of a starting instruction is accepted from the userthrough the operation section 103 (YES at step S901), the imageprocessing device 1 c transmits an original image reading instruction tothe scanner 2 through the input interface section 104 (S902) and thenwaits until image data is received from the scanner 2 (NO at step S903).When the scanner 2 receives the reading instruction from the imageprocessing device 1 c, it reads an image of an original set at apredetermined position to produce image data of the original andtransmits the resulting image data to the image processing device 1 c.It is to be noted that the image process starting instruction mayotherwise be inputted from a different device on the computer network 4or directly from the scanner 2. In this instance, the steps S901 andS902 are omitted.

[0093] When the image data is received from the scanner 2 through theinput interface section 104 (YES at step S903), the image processingdevice 1 c stores the received image data into the storage section 102and then uses the region extraction section 106 to separate characterregions, graphic regions and photograph regions from the input imagedata to extract individual region data (S904).

[0094] Then, the image processing device 1 c uses the region extractionsection 106 to complement the extracted character regions withperipheral pixels to prepare non-character image data from the inputimage data and store the non-character image data into the storagesection 102. Then, the region extraction section 106 discriminatesgraphic regions from the non-character image data to extract graphicregion data and store the graphic region data into the storage section102 together with position information of the regions.

[0095] Then, the region extraction section 106 complements the extractedgraphic regions of the non-character image data with peripheral pixelsto extract photograph region data from the non-character image data andstore the photograph region data into the storage section 102 togetherwith position information of the regions.

[0096] Thereafter, the image processing device 1 c uses the imageprocessing section 107 to perform an image process for each of theregion data extracted at step S904 in accordance with the region type ofthe region data (S905 to S907).

[0097]FIG. 15 is a flow chart illustrating a procedure of the characterregion process of the image processing device 1 c according to thepresent embodiment. Referring to FIG. 15, the image processing device 1c reads out character region data from the storage section 102 and usesthe character region processing section 107 a to perform a preprocessfor the character region data (S1001). More particularly, the imageprocessing device 1 c uses the character region processing section 107 ato detect a character color for each extracted character region data andbinarize the character region data into 1-bit data. Then, the imageprocessing device 1 c uses the character region processing section 107 ato calculate an image size for all of the character region data,compresses each of the character region data using the MMR compressionor the Flate compression in accordance with the image size and storesthe compressed character region data into the storage section 102together with position information and so forth of the same (S1002 toS1008). In particular, the character region number n of an object ofprocessing is initialized first (S1002), and the image size Sn of thecharacter region n is calculated (S1003). Then, the calculated imagesize Sn of the character region n is compared with a threshold value(S1004). If the image size Sn is equal to or greater than the thresholdvalue (YES at step S1004), then the character region n is compressedusing the MMR compression (S1005), but if the image size Sn is smallerthan the threshold value (NO at step S1004), then the character region nis compressed using the Flate compression (S1006). Then, the characterregion number n is successively incremented until it reaches a maximumvalue to repeat the steps S1004 to S1006 described above for allcharacter region data (S1007 and S1008).

[0098] As described hereinabove, the MMR compression is a compressionmethod suitable for character image regions totally from the point ofview of the picture quality, processing speed and compression ratio.However, where the MMR compression is used for a compression process forcharacter image data, if the character image data has an image sizesmaller than a predetermined image size, then the image size after thecompression process becomes greater than that before the compressionprocess. In contrast, where the Flate compression is applied tocompression of character region data, it is inferior to the MMRcompression in terms of all of the picture quality, processing speed andcompression ratio. However, the Flate compression exhibits a compressioneffect also with regard to character region data of a very small size inthat the image size after the compression process does not becomegreater than that before the compression process. Accordingly, thefollowing counter measure is taken in order to obtain image data with ahigh compression ratio while suppressing deterioration of the picturequality or reduction of the processing speed caused by a change of thecompression method to the minimum. In particular, a value across which,when character region data is compressed by the MMR compression, theimage size reverses before and after the compression process is set as athreshold value. Then, if character image data has an image size equalto or greater than the threshold value, then a compression process bythe MMR compression which is a default compression and is suitable for acharacter image region is performed for the character image data.However, if character image data has an image size smaller than thethreshold value, then a compression process by the Flate compressionwhich does not exhibit an increase of the image size after thecompression process with respect to the image size before thecompression process is performed in place of the MMR compression for thecharacter image data. It is to be noted that the threshold value used atstep S1004 preferably is 140 to 250 bytes in the image size after thebinarization at step S1001. However, the threshold value is not limitedto the range given above.

[0099] Further, referring back to FIG. 14, after a smoothing process, acolor subtraction process, a resolution conversion process and so forthare performed as a graphic region process for each graphic region databy the graphic region processing section 107 b, the Flate compression orsome other compression is performed as a reversible compression process,or the JPEG compression or some other compression is performed as anirreversible compression process. Then, resulting graphic region data isstored into the storage section 102 together with position informationthereof (S906). Meanwhile, a resolution conversion process, a smoothingprocess and other necessary processes for the photograph region data areperformed as a photograph region process by the photograph regionprocessing section 107 c, and then an irreversible compression processsuch as the JPEG process is performed for the photograph region data.Then, the resulting photograph region data is stored into the storagesection 102 together with position information thereof.

[0100] It is to be noted that the image processes of the characterregion process (S905), graphic region process (S906) and photographregion process (S907) maybe performed in any order.

[0101] Thereafter, the image processing device 1 c uses the regionsynthesis section 108 to synthesize the region data obtained by theimage processes described above based on the individual positioninformation to acquire composite image data and store the compositeimage data into the storage section 102 (S908). Further, the imageprocessing device 1 c uses the file format conversion section 109 toconvert the composite image data into composite image data of the outputfile format (S909). Then, the image processing device 1 c transmits theresulting output file (document image file) to the file server 3 throughthe output interface section 105 and the computer network 4 (S910).

[0102] When the output file is received from the image processing device1 c through the computer network 4, the file server 3 stores thereceived file into a predetermined directory of the storage device suchas a hard disk. Then, if a transfer request for the file is receivedfrom a different device on the computer network 4, then the file server3 transfers the stored file to the different device through the computernetwork 4.

[0103] In the embodiment described above, the threshold value for animage size to be used for discrimination of whether the MMR compressionshould be performed or the Flate compression should be performed foreach of character region data is set to a value across which the imagesize reverses before and after the compression process when thecharacter region data is compressed using the MMR compression. However,the present invention is not limited to this. For example, the thresholdvalue may otherwise be set to a value across which the image sizereverses after the compression process when character region data iscompressed using the MMR compression and the Flate compression.

[0104] Further, in the embodiment described above, the MMR compressionor the Flate compression is applied as a compression process forcharacter region data switchably in response to an image size. However,the present invention is not limited to the particular form, but acombination of compression methods different from those described abovemay be switchably applied to character region data, or a combination ofcompression methods same as or different from those described above maybe applied switchably to the other region data.

[0105] Further, in the embodiment described above, the image processingdevice of the present invention separates and extracts a characterregion, a graphic region and a photograph region from image data toperform the compression process individually for types of the regiondata. However, the present invention is not limited to this. Forexample, the image processing device of the present invention mayinterpret a document file described in a page description language, andextract a object which is a component of the document file to performthe compression process individually for types of the object data.

[0106] In the embodiments described above, the image inputting sourcedevice in the image processing system of the present invention is ascanner while the image outputting destination device is a file server.However, the image inputting source device is not limited particularlyif the image processing device of the present invention can acquireimage data from the same. Thus, the image inputting source device may bean device which includes image reading unit, image data preparationunit, image data reception unit, image processing unit, image datastorage unit or the like such as, for example, a facsimile device, amulti-function peripheral equipment (MFP) such as a digital copyingmachine, a digital camera, a personal computer, a work station, a serveror the like. Meanwhile, the image outputting destination device is notlimited particularly if it is an device which utilizes image dataacquired from the image processing device of the present invention.Thus, the image inputting source device may be an device which includesimage formation unit, image data transmission unit, image processingunit, image data storage unit or the like such as, for example, afacsimile device, a digital copying machine, a personal computer, a workstation, a server or the like. Further, the image processing device ofthe present invention may be an device for exclusive use which includessuch unit as mentioned above or may be formed as a computer for ascanner, a digital copying machine, a multi-function peripheralequipment (MFP) such as a facsimile device, a personal computer, a workstation, a server or the like combined with image reading unit, imagedata preparation unit, image data reception unit, image datatransmission unit, image formation unit, image data storage unit and soforth.

[0107] The image processing device according to the present inventioncan be implemented not only by a hardware circuit for exclusive use forexecuting the procedures described hereinabove but also by a CPUexecuting a specific program which describes the procedures describedhere in above. Where the present invention is implemented by the latter,the specific program described above for causing the image processingdevice to operate may be provided in the form of a computer-readablerecording medium such as a flexible disk or a CD-ROM or may otherwise beprovided on-line through a network such as the Internet. In thisinstance, the program recorded on a computer-readable recording mediumis usually transferred to and stored into a ROM, a hard disk or thelike. Further, the program may be provided as sole application softwareor may be incorporated in software of an image processing device as afunction of the device.

[0108] As described above, according to the present invention, an imageprocessing device which extracts character, graphic and photographregions from image data acquired by reading an original document andperforms image processing for the regions and then re-synthesizes themto prepare a document image file allows designation of a desiredcompression method for each region data. Therefore, an arbitrarycompression process can be performed for each of the region dataextracted from the input data. Further, according to the presentinvention, the image processing device automatically performs, inresponse to designation of a compression process mode, a compressionprocess for each region data using an optimum compression method.Therefore, even if the user does not have particular knowledge ofcompression methods to be applied to the individual region data, desiredcompression processes can be executed for the region data.

[0109] Further, according to the present invention, in a case whereinexecution of a compression process for specific region data using adefault compression method, that is, a compression method suitable forthe region results in increase of the image size after the compressionprocess of region data whose image size is smaller than a predeterminedvalue (threshold value) with respect to the image size before thecompression process, the image processing device described abovecalculates the image size of the specific region data in advance andthen performs, if the region data exhibits an image size equal to orgreater than the threshold value, a compression process for the regiondata using the default compression method, but performs, if the regiondata exhibits an image size smaller than the threshold value, acompression process for the region data using a compression method whichdoes not make the image size after the compression process greater thanthat before the compression process even if the image size is smallerthan the threshold value. Therefore, image data can be obtained with ahigh compression ratio while deterioration of the picture quality andreduction of the processing speed by a change of the compression methodare suppressed to the minimum.

[0110] The present invention is not limited to the details of the abovedescribed preferred embodiments. The scope of the invention is definedby the appended claims and all changes and modifications as fall withinthe equivalence of the scope of the claims are therefore to be embracedby the invention.

What is claimed is:
 1. An image processing device, comprising: a regionextraction unit for separating and extracting a character region, agraphic region and a photograph region from image data; a regioncompression unit for performing a compression process for each of theregion data extracted by said region extraction unit; a region synthesisunit for synthesizing the region data compressed by said regioncompression unit; and a compression method selection unit for selectinga compression method of the compression process to be performed for eachof the region data extracted by said region extraction unit from among aplurality of compression methods designated individually for types ofthe region data; said region compression unit performing the compressionprocess for each of the region data using the compression methodselected for the region data by said compression method selection unit.2. An image processing device, comprising: a region extraction unit forseparating and extracting a character region, a graphic region and aphotograph region from image data; a region compression unit forperforming a compression process for each of the region data extractedby said region extraction unit; a region synthesis unit for synthesizingthe region data compressed by said region compression unit; and acompression process mode setting unit for setting a speed preferencemode as a compression process mode; said region compression unit using,when the speed preference mode is set by said compression process modesetting unit, one of a plurality of compression methods designated foreach of the region data which exhibits the highest processing speed toperform the compression process for the individual region data.
 3. Animage processing device, comprising: a region extraction unit forseparating and extracting a character region, a graphic region and aphotograph region from image data; a region compression unit forperforming a compression process for each of the region data extractedby said region extraction unit; a region synthesis unit for synthesizingthe region data compressed by said region compression unit; and acompression process mode setting unit for setting a picture qualitypreference mode as a compression processing mode; said regioncompression unit using, when the picture quality preference mode is setby said compression process mode setting unit, one of a plurality ofcompression methods designated for each of the region data whichexhibits the least picture quality deterioration to perform thecompression process for the individual region data.
 4. An imageprocessing device, comprising: a region extraction unit for separatingand extracting a character region, a graphic region and a photographregion from image data; a region compression unit for performing acompression process for each of the region data extracted by said regionextraction unit; a region synthesis unit for synthesizing the regiondata compressed by said region compression unit; and a compressionprocess mode setting unit for setting a size preference mode as acompression processing mode; said region compression unit using, whenthe size preference mode is set by said compression process mode settingunit, one of a plurality of compression methods designated for each ofthe region data which exhibits the highest compression ratio to performthe compression process for the individual region data.
 5. An imageprocessing device, comprising: a region extraction unit for separatingand extracting a character region, a graphic region and a photographregion from image data; a region compression unit for performing acompression process for each of the region data extracted by said regionextraction unit; a region synthesis unit for synthesizing the regiondata compressed by said region compression unit; and a compressionprocess mode setting unit for setting a speed preference mode, a picturequality preference mode or a size preference mode as a compressionprocessing mode; said region compression unit using, when the speedpreference mode is set by said compression process mode setting unit,one of a plurality of compression methods designated for each of theregion data which exhibits the highest processing speed to perform thecompression process for the individual region data, said regioncompression unit using, when the picture quality preference mode is setby said compression process mode setting unit, one of a plurality ofcompression methods designated for each of the region data whichexhibits the least picture quality deterioration to perform thecompression process for the individual region data, and said regioncompression unit using, when the size preference mode is set by saidcompression process mode setting unit, one of a plurality of compressionmethods designated for each of the region data which exhibits thehighest compression ratio to perform the compression process for theindividual region data.
 6. An image processing device, comprising: aobject extraction unit for interpreting a document file described in apage description language, and extracting a object which is a componentof the document file, a object compression unit for performing acompression process for each of the object data extracted by said objectextraction unit; a object synthesis unit for synthesizing the objectdata compressed by said object compression unit; and a compressionmethod selection unit for selecting a compression method of thecompression process to be performed for each of the object dataextracted by said object extraction unit from among a plurality ofcompression methods designated individually for types of the objectdata; said object compression unit performing the compression processfor each of the object data using the compression method selected forthe object data by said compression method selection unit.
 7. An imageprocessing method, comprising: a region extraction step of separatingand extracting a character region, a graphic region and a photographregion from image data; a region compression step of performing acompression process for each of the region data extracted by said regionextraction step; a region synthesis step of synthesizing the region datacompressed by said region compression step; and a compression methodselection step of selecting a compression method of the compressionprocess to be performed for each of the region data extracted by saidregion extraction step from among a plurality of compression methodsdesignated individually for types of the region data; said regioncompression step performing the compression process for each of theregion data using the compression method selected for the region data bysaid compression method selection step.
 8. An image processing method,comprising: a region extraction step of separating and extracting acharacter region, a graphic region and a photograph region from imagedata; a region compression step of performing a compression process foreach of the region data extracted by said region extraction step; aregion synthesis step of synthesizing the region data compressed by saidregion compression step; and a compression process mode setting step ofsetting a speed preference mode as a compression process mode; saidregion compression step using, when the speed preference mode is set bysaid compression process mode setting step, one of a plurality ofcompression methods designated for each of the region data whichexhibits the highest processing speed to perform the compression processfor the individual region data.
 9. An image processing method,comprising: a region extraction step of separating and extracting acharacter region, a graphic region and a photograph region from imagedata; a region compression step of performing a compression process foreach of the region data extracted by said region extraction step; aregion synthesis step of synthesizing the region data compressed by saidregion compression step; and a compression process mode setting step ofsetting a picture quality preference mode as a compression processingmode; said region compression step using, when the picture qualitypreference mode is set by said compression process mode setting step,one of a plurality of compression methods designated for each of theregion data which exhibits the least picture quality deterioration toperform the compression process for the individual region data.
 10. Animage processing method, comprising: a region extraction step ofseparating and extracting a character region, a graphic region and aphotograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression process mode setting step of setting a size preference modeas a compression processing mode; said region compression step using,when the size preference mode is set by said compression process modesetting step, one of a plurality of compression methods designated foreach of the region data which exhibits the highest compression ratio toperform the compression process for the individual region data.
 11. Animage processing method, comprising: a region extraction step ofseparating and extracting a character region, a graphic region and aphotograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression process mode setting step of setting a speed preferencemode, a picture quality preference mode or a size preference mode as acompression processing mode; said region compression step using, whenthe speed preference mode is set by said compression process modesetting step, one of a plurality of compression methods designated foreach of the region data which exhibits the highest processing speed toperform the compression process for the individual region data, saidregion compression step using, when the picture quality preference modeis set by said compression process mode setting step, one of a pluralityof compression methods designated for each of the region data whichexhibits the least picture quality deterioration to perform thecompression process for the individual region data, and said regioncompression step using, when the size preference mode is set by saidcompression process mode setting step, one of a plurality of compressionmethods designated for each of the region data which exhibits thehighest compression ratio to perform the compression process for theindividual region data.
 12. An image processing program for causing animage processing device to execute: a region extraction step ofseparating and extracting a character region, a graphic region and aphotograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression method selection step of selecting a compression method ofthe compression process to be performed for each of the region dataextracted by said region extraction step from among a plurality ofcompression methods designated individually for types of the regiondata; said region compression step performing the compression processfor each of the region data using the compression method selected forthe region data by said compression method selection step.
 13. An imageprocessing program for causing an image processing device to execute: aregion extraction step of separating and extracting a character region,a graphic region and a photograph region from image data; a regioncompression step of performing a compression process for each of theregion data extracted by said region extraction step; a region synthesisstep of synthesizing the region data compressed by said regioncompression step; and a compression process mode setting step of settinga speed preference mode as a compression process mode; said regioncompression step using, when the speed preference mode is set by saidcompression process mode setting step, one of a plurality of compressionmethods designated for each of the region data which exhibits thehighest processing speed to perform the compression process for theindividual region data.
 14. An image processing program for causing animage processing device to execute: a region extraction step ofseparating and extracting a character region, a graphic region and aphotograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression process mode setting step of setting a picture qualitypreference mode as a compression processing mode; said regioncompression step using, when the picture quality preference mode is setby said compression process mode setting step, one of a plurality ofcompression methods designated for each of the region data whichexhibits the least picture quality deterioration to perform thecompression process for the individual region data.
 15. An imageprocessing program for causing an image processing device to execute: aregion extraction step of separating and extracting a character region,a graphic region and a photograph region from image data; a regioncompression step of performing a compression process for each of theregion data extracted by said region extraction step; a region synthesisstep of synthesizing the region data compressed by said regioncompression step; and a compression process mode setting step of settinga size preference mode as a compression processing mode; said regioncompression step using, when the size preference mode is set by saidcompression process mode setting step, one of a plurality of compressionmethods designated for each of the region data which exhibits thehighest compression ratio to perform the compression process for theindividual region data.
 16. An image processing program for causing animage processing device to execute: a region extraction step ofseparating and extracting a character region, a graphic region and aphotograph region from image data; a region compression step ofperforming a compression process for each of the region data extractedby said region extraction step; a region synthesis step of synthesizingthe region data compressed by said region compression step; and acompression process mode setting step of setting a speed preferencemode, a picture quality preference mode or a size preference mode as acompression processing mode; said region compression step using, whenthe speed preference mode is set by said compression process modesetting step, one of a plurality of compression methods designated foreach of the region data which exhibits the highest processing speed toperform the compression process for the individual region data, saidregion compression step using, when the picture quality preference modeis set by said compression process mode setting step, one of a pluralityof compression methods designated for each of the region data whichexhibits the least picture quality deterioration to perform thecompression process for the individual region data, and said regioncompression step using, when the size preference mode is set by saidcompression process mode setting step, one of a plurality of compressionmethods designated for each of the region data which exhibits thehighest compression ratio to perform the compression process for theindividual region data.
 17. A computer-readable recording medium onwhich the image processing program according to claim 16 is recorded.18. An image processing device, comprising: a region extraction unit forseparating and extracting a character region, a graphic region and aphotograph region from image data; a region compression unit forperforming a compression process for each of the region data extractedby said region extraction unit; a region synthesis unit for synthesizingthe region data compressed by said region compression unit; and an imagesize calculation unit for calculating an image size of specific regiondata extracted by said region extraction unit; said region compressionunit using, when the image size of the specific region data calculatedby said image size calculation unit is equal to or greater than athreshold value, a first compression method to perform the compressionprocess for the specific region data, and said region compression unitusing, when the image size of the specific region data calculated bysaid image size calculation unit is smaller than the threshold value, asecond compression method to perform the compression process for thespecific region data.
 19. The image processing device according to claim18, wherein, the first compression method is a compression method inwhich the image size after the compression process is greater than theimage size before the compression process, when it is applied to thespecific region data whose image size before the compression process issmaller than the threshold value, and the second compression method is acompression method in which the image size after the compression processis not greater than the image size before the compression process, whenit is applied to the specific region data whose image size before thecompression process is smaller than the threshold value.
 20. The imageprocessing device according to claim 18, wherein the first compressionmethod is a default compression method for the specific region data. 21.The image processing device according to claim 18, wherein the specificregion data is character region data.
 22. The image processing deviceaccording to claim 21, wherein the first compression method is the MMRcompression and the second compression method is the Flate compression.23. An image processing device, comprising: a object extraction unit forinterpreting a document file described in a page description language,and extracting a object which is a component of the document file, aobject compression unit for performing a compression process for each ofthe object data extracted by said object extraction unit; a objectsynthesis unit for synthesizing the object data compressed by saidobject compression unit; an image size calculation unit for calculatingan image size of the object data extracted by said object extractionunit; and a compression method selection unit for selecting acompression method of the compression process to be performed for eachof the object data extracted by said object extraction unit inproportion to the image size of the object data calculated by said imagesize calculation unit from among a plurality of designated compressionmethods; said object compression unit performing the compression processfor each of the object data using the compression method selected forthe object data by said compression method selection unit.
 24. The imageprocessing device according to claim 23, wherein, said compressionmethod selection unit selecting, when the image size of the object datacalculated by said image size calculation unit is equal to or greaterthan a threshold value, a first compression method to perform thecompression process for the object data, and said compression methodselection unit selecting, when the image size of the object datacalculated by said image size calculation unit is smaller than thethreshold value, a second compression method to perform the compressionprocess for the object data.
 25. The image processing device accordingto claim 24, wherein, the first compression method is a compressionmethod in which the image size after the compression process is greaterthan the image size before the compression process, when it is appliedto the object data whose image size before the compression process issmaller than the threshold value, and the second compression method is acompression method in which the image size after the compression processis not greater than the image size before the compression process, whenit is applied to the object data whose image size before the compressionprocess is smaller than the threshold value.
 26. An image processingmethod, comprising: a region extraction step of separating andextracting a character region, a graphic region and a photograph regionfrom image data; a region compression step of performing a compressionprocess for each of the region data extracted by said region extractionstep; a region synthesis step of synthesizing the region data compressedby said region compression step; and an image size calculation step ofcalculating an image size of specific region data extracted by saidregion extraction step; said region compression step using, when theimage size of the specific region data calculated by said image sizecalculation step is equal to or greater than a threshold value, a firstcompression method to perform the compression process for the specificregion data, and said region compression step using, when the image sizeof the specific region data calculated by said image size calculationstep is smaller than the threshold value, a second compression method toperform the compression process for the specific region data.
 27. Theimage processing method according to claim 26, wherein, the firstcompression method is a compression method in which the image size afterthe compression process is greater than the image size before thecompression process, when it is applied to the specific region datawhose image size before the compression process is smaller than thethreshold value, and the second compression method is a compressionmethod in which the image size after the compression process is notgreater than the image size before the compression process, when it isapplied to the specific region data whose image size before thecompression process is smaller than the threshold value.
 28. The imageprocessing method according to claim 26, wherein the first compressionmethod is a default compression method for the specific region data. 29.The image processing method according to claim 26, wherein the specificregion data is character region data.
 30. The image processing methodaccording to claim 29, wherein the first compression method is the MMRcompression and the second compression method is the Flate compression.31. An image processing method, comprising: a character regionextraction step of separating and extracting character regions fromimage data; an image size calculation step of calculating an image sizeof each of the character region data extracted by said character regionextraction step; a compression method selection step of selecting, whenthe image size of each of the character region data calculated by saidimage size calculation step is equal to or greater than a thresholdvalue, the MMR compression as a compression method but selecting, whenthe image size of each of the character region data calculated by saidimage size calculation step is smaller than the threshold value, theFlate compression as a compression method; and a region compression stepof performing a compression process for each of the character regiondata using the compression method selected by said compression methodselection step.
 32. An image processing program for causing an imageprocessing device to execute: a region extraction step of separating andextracting a character region, a graphic region and a photograph regionfrom image data; a region compression step of performing a compressionprocess for each of the region data extracted by said region extractionstep; a region synthesis step of synthesizing the region data compressedby said region compression step; and an image size calculation step ofcalculating an image size of specific region data extracted by saidregion extraction step; said region compression step using, when theimage size of the specific region data calculated by said image sizecalculation step is equal to or greater than a threshold value, a firstcompression method to perform the compression process for the specificregion data, and said region compression step using, when the image sizeof the specific region data calculated by said image size calculationstep is smaller than the threshold value, a second compression method toperform the compression process for the specific region data.
 33. Theimage processing program according to claim 32, wherein, the firstcompression method is a compression method in which the image size afterthe compression process is greater than the image size before thecompression process, when it is applied to the specific region datawhose image size before the compression process is smaller than thethreshold value, and the second compression method is a compressionmethod in which the image size after the compression process is notgreater than the image size before the compression process, when it isapplied to the specific region data whose image size before thecompression process is smaller than the threshold value.
 34. The imageprocessing program according to claim 32, wherein the first compressionmethod is a default compression method for the specific region data. 35.The image processing program according to claim 32, wherein the specificregion data is character region data.
 36. The image processing programaccording to claim 35, wherein the first compression method is the MMRcompression and the second compression method is the Flate compression.37. The computer-readable recording medium on which the image processingprogram according to claim 32 is recorded.
 38. An image processingprogram for causing an image processing device to execute: a characterregion extraction step of separating and extracting character regionsfrom image data; an image size calculation step of calculating an imagesize of each of the character region data extracted by said characterregion extraction step; a compression method selection step ofselecting, when the image size of each of the character region datacalculated by said image size calculation step is equal to or greaterthan a threshold value, the MMR compression as a compression method butselecting, when the image size of each of the character region datacalculated by said image size calculation step is smaller than thethreshold value, the Flate compression as a compression method; and aregion compression step of performing a compression process for each ofthe character region data using the compression method selected by saidcompression method selection step.
 39. The computer-readable recordingmedium on which the image processing program according to claim 38 isrecorded.